Computer Science 210
Data Structures
Fall 2019, Siena College
DoublePair BlueJ Project
Click here to download a BlueJ project for DoublePair.
DoublePair Source Code
The Java source code for DoublePair is below. Click on a file name to download it.
/**
* Example DoublePair: a class that holds a pair of double values.
*
* @author Jim Teresco, The College of Saint Rose, CSC 523, Summer 2014
* Updated for CSIS 210, Siena College, Fall 2016
* @version Fall 2019
*/
public class DoublePair {
// we'll need, of course, two double values as instance variables
private double first, second;
/**
* Construct a new DoublePair.
*
* @param first the first item in the pair
* @param second the second item in the pair
*/
public DoublePair(double first, double second) {
this.first = first;
this.second = second;
}
/**
* Get the first item in the pair
*
* @return the first item in the pair
*/
public double getFirst() {
return first;
}
/**
* Get the second item in the pair
*
* @return the second item in the pair
*/
public double getSecond() {
return second;
}
/**
* Modify the first item in the pair
*
* @param newFirst the new first item in the pair
*/
public void setFirst(double newFirst) {
first = newFirst;
}
/**
* Modify the second item in the pair
*
* @param newSecond the new first item in the pair
*/
public void setSecond(double newSecond) {
second = newSecond;
}
/**
* Modify both items in the pair
*
* @param newFirst the new first item in the pair
* @param newSecond the new first item in the pair
*/
public void setValues(double newFirst, double newSecond) {
first = newFirst;
second = newSecond;
}
/**
* Return a String to make this look like a coordinate pair (seems as
* good as anything and likely to be useful in many contexts).
*
* @return the numbers in the pair, in parentheses separated by a comma
*/
@Override
public String toString() {
return "(" + first + ", " + second + ")";
}
/**
* Check for equality of this DoublePair with another, defined by both
* items in the pair being equal to those in the other pair.
*
* @param o the other DoublePair
* @return whether this DoublePair is equal to o
*/
@Override
public boolean equals(Object o) {
DoublePair other = (DoublePair)o;
return (other.first == first) && (other.second == second);
}
/**
* main method to run some test cases.
*
* @param args not used.
*/
public static void main(String args[]) {
// we'll create a few DoublePair objects and print them out
DoublePair a = new DoublePair(4.3, 9.1);
DoublePair b = new DoublePair(0, 0);
System.out.println("a: " + a);
System.out.println("b: " + b);
// try out the accessors
System.out.println("a.getFirst(): " + a.getFirst());
System.out.println("a.getSecond(): " + a.getSecond());
System.out.println("b.getFirst(): " + b.getFirst());
System.out.println("b.getSecond(): " + b.getSecond());
// are they equal?
System.out.println("a.equals(b): " + a.equals(b));
// mutators!
a.setFirst(17.0);
a.setSecond(-23.5);
b.setValues(17.0, -23.5);
System.out.println("a: " + a);
System.out.println("b: " + b);
// are they equal now? Hope so!
System.out.println("a.equals(b): " + a.equals(b));
// uncomment the following to see what happens if we send
// the wrong type of object to the equals method
//System.out.println("a.equals(\"hi there\"): " + a.equals("high there"));
}
}